1. A polymer for regulating drug release based on shape memory, which is characterized in that: the network center is D₄ ^viThe network chain contains P (VAc-AA) compatibilization and hydrophilic segment and PTMG soft segment

The molecular structure is as follows:

a polymer based on shape memory for regulating and controlling the release of medicine has a molecular network center D₄ ^viThe structure is as follows:

a polymer for regulating and controlling drug release based on shape memory has a structure that a molecular network chain contains a P (VAc-AA) compatibilization and hydrophilic segment as follows:

m is an integer greater than 1

A polymer for regulating and controlling drug release based on shape memory has the following structure of PTMG soft segment on a molecular network chain:

and n is an integer greater than 1.

Background

The phenomenon that a solid material with a certain shape is subjected to plastic deformation under the stimulation of certain external conditions, and the material is completely restored to the shape before deformation after the stimulation of a specific environment is called shape memory effect. Depending on different environmental conditions for realizing memory function, the memory materials can be classified into temperature-sensitive type, water-sensitive type, photosensitive type, acid-base sensitive type and the like, and the most applied and researched at present are thermotropic shape memory and water-induced shape memory polymer materials.

PLA is used as a wide range of biodegradable polyesters, often used as a tissue engineering scaffold as a drug delivery material. Shape memory, which is a process of rearrangement of polymer molecular chains, is combined therewith. By adding synthetic monomers into PLA and using the monomers as starting materials, the PLA has a shape memory function, so that a multifunctional system combining shape memory capacity, biodegradability and controllable drug release is obtained.

Disclosure of Invention

In order to achieve the purpose, the invention provides a polymer for regulating and controlling drug release based on shape memory, which has the advantages of simple recovery condition, short recovery time, controlled drug release speed and effectively improved toughness and hydrophilicity of polylactic acid.

The technical scheme of the invention is as follows: synthesizing a compound D₄ ^viAs a center, PTMG: (T _g (iii) = -76 ℃) soft segment, P (VAc-AA) compatibilized and hydrophilic segment network polymer PMVS flexible block, blend PLA: (T _g = 62 ℃). Since the synthetic polymers have good water absorption and are compatible with PLAT _g The phase difference is large, so that the shape memory of PLA is realized through water absorption in a water environment and heat assistance, and a network-shaped polymer chain moves in the shape recovery process, so that the drug release is accelerated.

The polymer for regulating and controlling the drug release based on the shape memory has a molecular network center D₄ ^viThe structure is as follows:

。

the polymer for regulating and controlling drug release based on shape memory has the following structure that a molecular network chain contains a P (VAc-AA) compatibilization segment and a hydrophilic segment:

and m is an integer greater than 1.

The polymer for regulating and controlling drug release based on shape memory has the following structure of PTMG soft segment on the molecular network chain:

and n is an integer greater than 1.

Drawings

FIG. 1 is a NMR spectrum of a network polymer.

As shown in FIG. 1, in the nuclear magnetic spectrum, D is between a (0 ppm to 0.4ppm)₄ ^vimeso-Si-CH₃Chemical shifts of hydrogen, b (1.56ppm) and f (3.33ppm) being-CH in PTMG₂Chemical shifts of hydrogen, c (1.78ppm) and d (1.95ppm) being respectively-CH in VAc₂-and-CH₃Chemical shifts of hydrogen, e (2.22ppm) and g (3.61ppm) being-CH in AGE₂Chemical shifts of the hydrogen, the occurrence of a chemical shift of the hydrogen on the carboxyl group around i (12.24ppm) indicates AA polymerization. By using¹The results of the characterization by H-NMR indicate that one is represented by D₄ ^viAs a center, PTMG as a soft segmentNetwork polymers of P (VAc-AA) compatibilized and hydrophilic segments have been synthesized.

FIG. 2 is the process of shape memory of the network polymer and PLA blended film prepared by the invention. A is the 60 ℃ heat recovery and B is the recovery in water (a-initial shape, B-temporary shape, c-post-recovery shape).

FIG. 3 shows the drug release of the network polymer and PLA blended film prepared by the invention at different temperatures (A is 25 ℃ release, B is 37 ℃ release).

Detailed Description

The present invention will be specifically described below by way of examples.

Example 1:

weighing a proper amount of PTMG and Allyl Glycidyl Ether (AGE), placing the PTMG and the AGE in an ampoule bottle provided with a magnetic stirring rod, introducing nitrogen, stirring a certain amount of tetrahydrofuran solvent at 65 ℃ for 45min, heating to 125 ℃, dropwise adding concentrated sulfuric acid (tetrahydrofuran diluted) catalyst for reaction for 5h, and refluxing deionized water for 1h to terminate the reaction. After the reaction, the mixture is separated into layers, the upper solution is distilled under reduced pressure to remove the unreacted monomer, and the product is dried in vacuum for 12 hours at the temperature of 40 ℃. And (2) placing the product obtained by the previous step and a certain amount of VAc into a three-neck flask, introducing nitrogen, taking tetrahydrofuran as a solvent, taking azodiisobutyronitrile as a catalyst, controlling the temperature to 65 ℃, dropwise adding AA through a titration funnel, reacting for 5 hours, and obtaining a network-shaped product, settling and drying.

PLA and a network polymer (containing 10wt% of salicylic acid) are respectively dissolved in chloroform and a tetrahydrofuran solvent according to the mass ratio of 7:3, then the mixture is uniformly mixed, wherein the concentration of the PLA and the network polymer is 29wt%, and the mixture is stirred at room temperature overnight. The overnight stirred solution was poured onto a glass plate and the solution was allowed to flow freely onto the glass plate. Naturally volatilizing at normal temperature (about 20 ℃) and normal pressure for 2 hours, curing the film in the air, then processing and forming the sample strip, fixing the shape after 2 days, and then vacuumizing and drying at 25 ℃ for later use.

The formed film is placed in an environment at 60 ℃ for a period of time and then fixed in a temporary shape. The polymer network can be placed in an environment and water at 60 ℃ respectively to recover the original shape rapidly, which shows that the network polymer can endow PLA water and a heat-induced shape memory function.

PLA/salicylic acid and PLA/network/salicylic acid mixed films 20mg were placed in 20ml of ph =7.4 phosphate buffer solution at 25 ℃ and 37 ℃ respectively and tested for salicylic acid release at different times.